datsun 521 ute Posted March 11, 2012 Report Share Posted March 11, 2012 I was just wondering why the rear wheel cylinders are twin piston and fronts are single piston? Would this then mean the rears would be getting better and more even grab on the surface area of the shoes in the rear drums? If so could you use a twin piston wheel cylinder on the fronts and also use the rear shoes so they fit? Just curious. Quote Link to comment
flatcat19 Posted March 11, 2012 Report Share Posted March 11, 2012 Weird. The rears on my 521 are singles. Quote Link to comment
mklotz70 Posted March 11, 2012 Report Share Posted March 11, 2012 It has something to do with the fronts being "self actuating" If you google that, you might get a better answer. The fronts do 80% of the braking.....if the rears were actually a better setup, they'd be locking up all the time. You'd be far better off converting to discs up front.....but the front drums work just fine if you have them setup correctly with good components. flat....I'm pretty sure he's referring to how the front only push out one side of the wheel cyl and the rears push out both sides. I'm pretty sure there's only one wheel cylinder in his rear brakes......but I could be wrong....Australian models were a bit different. Quote Link to comment
datsun 521 ute Posted March 11, 2012 Author Report Share Posted March 11, 2012 Both front and rear drums ony have the one wheel cylinder but rear has a twin piston cylinder. In googling I found this pretty in detail and interesting article about disc brakes http://www.hotrodheaven.com/tech/brakes/ But also found this on self actuating. http://auto.howstuffworks.com/auto-parts/brakes/brake-types/drum-brake1.htm From what I can gather the rears are also self actuating. My thought was they might have put a twin piston in because it being a commercial vehicle and the 1 tonne load capacity it has, to help the rear braking when it has a load in the tray. All the passenger cars I have worked on with 4 wheel drums normally have twin piston cylinder in the front drums and single in the rear. And my 1500 Fairlady had two single piston cylinders in the front, 1 top and 1 bottom, and a single in the rear. Quote Link to comment
mklotz70 Posted March 11, 2012 Report Share Posted March 11, 2012 Those are normal wheel cylinders....same thing we have on all of ours. I'm thinking that the dual piston would have half the travel and pressure....helping to bias the braking since it was on a single circuit master cylinder. GREAT links!! I'm definitely going to have to read the Dean Oshiro one completely! :) Quote Link to comment
flatcat19 Posted March 11, 2012 Report Share Posted March 11, 2012 Very odd. Cuz mine has the same cylinders F & R. Single piston/push. Maybe that is one of the problems with my brakes. Previous owner was such a hack job. Disc brake parts aren't showing up fast enough at my place. Quote Link to comment
mklotz70 Posted March 11, 2012 Report Share Posted March 11, 2012 Now that you mention it....I think he has the 520 style up front. Sorry.....the only time I look at front drums is when I'm taking them off to put discs on :) Quote Link to comment
flatcat19 Posted March 11, 2012 Report Share Posted March 11, 2012 Well, all 4 wheels on mine look like the first picture. Havn't check much to see he PO hacked the wrong WC onto the back. Quote Link to comment
mklotz70 Posted March 11, 2012 Report Share Posted March 11, 2012 The factory manual shows the same thing he has..... pg 137 (pdf page) http://www.davidcmurphy.com/olddat/data/Service_Manual_Datsun_Pick-up_Model_521_Series_Chassis_and_Body.pdf 1 Quote Link to comment
skyblue Posted May 28, 2012 Report Share Posted May 28, 2012 hey guys sorry to thread jack but does anyone know the difference between 13/16 bore and 3/4 bore wheel cylinders? I just bought some 13/16 bore rear wheel cylinders from rockauto and the y pipe dont fit on new ones. Quote Link to comment
mklotz70 Posted May 28, 2012 Report Share Posted May 28, 2012 They may be from a 620 and may be metric. Quote Link to comment
banzai510(hainz) Posted May 29, 2012 Report Share Posted May 29, 2012 I had good luck fitting rear wheel cyl. 3/4 or 13/16 isnt much difference. Mine always fit. ck the part number. However the taiwan or Italian made ones dont last 5 years. if you have new washers you could use the old Y fitting to make you brake line Quote Link to comment
skyblue Posted May 30, 2012 Report Share Posted May 30, 2012 I had good luck fitting rear wheel cyl. 3/4 or 13/16 isnt much difference. Mine always fit. ck the part number. However the taiwan or Italian made ones dont last 5 years. if you have new washers you could use the old Y fitting to make you brake line well I was planning on reusing the old Y fitting, the problem is the Y fitting has different thread size than the new replacement (Dorman brand). I don't get it. I have to call rockauto and see wtf. Quote Link to comment
banzai510(hainz) Posted May 30, 2012 Report Share Posted May 30, 2012 Just reuse the old Y fitting and if the new Y fitting had the new washers and use them. he 521 front cylinders show a picture of the fitting but when I got them from Rockauto they didnt have the bleed screws or Y fitting . I called rockauto and they called the manf and no they do not come with them. I told them I only order those cause of the photo is was complete. Maybe the cylinder you got was a later 620 type (which could be metric but Im not a 620 expert) Quote Link to comment
DanielC Posted May 30, 2012 Report Share Posted May 30, 2012 I believe the difference between 521 rear wheel cylinders and 620 wheel cylinders is only the threads.on a 521, the studs that hold the wheel cylinder to the backing plate are 5/16-24, on a 620 the threads are M8-1.0, or M8-1.25.The flare nut fittings on a 521 are 3/8-24, on a 620 are M10-1.0. I believe the same thread is used for the "banjo" bolt fitting the brake line attaches to the wheel cylinder. Quote Link to comment
glorydime Posted January 23, 2014 Report Share Posted January 23, 2014 Anyone had both 3/4 and 13/16 not work? My bleeder and y won't go in for the fronts. T101 is the casting on the side of the wheel cylinder. I've tried rockauto and napa both sizes just won't take the y pipe. Quote Link to comment
ggzilla Posted January 23, 2014 Report Share Posted January 23, 2014 Yep. The late ones have different threads. Perhaps a previous owner changed over to the other type? Quote Link to comment
glorydime Posted January 24, 2014 Report Share Posted January 24, 2014 Damn, well I can't seem to find any bleeders or y pipes or I'd just switch over. Any options y'all can think I have? I'm thinking the repair kit is all I have. Quote Link to comment
ggzilla Posted January 24, 2014 Report Share Posted January 24, 2014 Repair kits work perfect - if the bores are not pitted. Quote Link to comment
banzai510(hainz) Posted January 25, 2014 Report Share Posted January 25, 2014 try Rockauto.com I had bought some new wheel cylinders a few yrs ago. But had proplems with bleeders if I remember right Quote Link to comment
DanielC Posted January 25, 2014 Report Share Posted January 25, 2014 You maybe can try the local Nissan dealer. high quality, includes the "Y", and a new bleeder. This is a more expensive way to go, but it is your brakes. On a vehicle with only a single reservoir, and hydraulic system, on the master cylinder. Quote Link to comment
glorydime Posted January 26, 2014 Report Share Posted January 26, 2014 I tried rock autos even different brands, none fit, I'm gonna try a repair kit for now and upgrade to disc after that. Quote Link to comment
glorydime Posted January 26, 2014 Report Share Posted January 26, 2014 Thanks Daniel I'll try this option. Quote Link to comment
glorydime Posted February 2, 2014 Report Share Posted February 2, 2014 well, I still can't seem to get this going, i tried all the nissan dealerships and none offer y pipes, I tried a repair kit to only have it leak after I cleaned everything up and made sure it wasn't scored. Anyone else have an option, is there a conversion I can run? or anything, I want my truck back on the road. Quote Link to comment
ggzilla Posted February 2, 2014 Report Share Posted February 2, 2014 Sounds like someone already converted your to 620 cylinders. Quote Link to comment
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